Spark-plug tester



Jan. 28, 1930. FlSCHER 1,745,157

SPARK PLUG 'TESTER Filed Jan. 20, 1927 \NVENTOZ HTTQBNEY Patented Jan. 28, 1930 UNITED STATES PATENT OF'ICE SPARK-PLUG rnsrnn Application filed January 20, 1927. Serial No. 162,379.

This invention relatesto certain new and useful improvements in spark plug testers, and the primary object thereof is to provide a novel, improved and simplified type of device for short circuiting the plugs of an internal combustion engine so as to confine the explosion to but one cylinder to enable location of the defective plug.

A. still further object of the invention is to provide a spark plug tester which is of economical construction and which can be easily and quickly applied to and removed from the plugs.

The invention has still further and other objects which will hereinafter be set forth and manifested in the course of the following description.

In the drawings Figure 1 is a side elevation of the invention applied to a spark plug, a fragmentary section of the engine cylinder being shown;

Figure 2 is an end view of the same;

Figure 3 is a top plan view of the device, partly in broken section; and

Figure 4 is a view similar to Fig. 1, showing use of the invention in connection with motors of the type wherein the plug is received in a countersunk socket.

In proceeding in accordance with the present invention, a pair of similar members 1 of wood or other material non-conductive of electric current, are employed, the same being pivotally connected by means of a spring wire. The wire is bent to form L-shaped arms 3 and 4c, the transverse end portions 3 and 4 of the arms being disposed in transverse grooves 5 and 6, respectively, formed in the outer sides of the members 1, while the longitudinal members of the arms lie adjacent to the sides of the members and incline in opposite directions. The arms 3 and t are curved into coil form, as illustrated at 7 in Fig. 3, and are thence joined by a transverse intermediate portion 8 of the wire which lies between the members 1, as shown.

The members 1 are recessed at 9 to form opposing aws 10, and the latter have flexible spring fingers 11, preferably formed of sheet metal, secured thereto on their inner sides by means of hollow rivets 12. The rivets 12 are arranged so as to engage opposite sides of the usual nut 13 mounted on the upper end of the spark plug electrode 14:.

As depicted in Figs. 1 and 2 of the drawings, the resilient fingers 11 are disposed at ight angles to the plane of the members 1. In use of the invention, with the members 1 arranged horizontally and with their rivets l9. gripping the spark plug nut 13, the fingers 11 engage the metal body 15 of the spark plug and thereby short-circuit the latter so as to prevent the current passing through the electrode. It will be understood that in testing the spark plugs of a four cylinder motor, three of the devices are preferably employed, and, in testing a six cylinder motor, five of the devices are preferably employed, the devices being successively applied to the various spark plugs so that one of the latter is alone in circuit for a length of time to ascertain whether same is functioning properly.

In Fig. 4: wherein. a type of engine head having a countersunk socket S is illustrated, the members 1 are disposed substantially horizontally, resting on or against the cylinder block so as to effect short circuiting of the plug.

It will be seen that the invention is adapted for use with two different types of motors and with the members 1 and the fingers disposed either vertically or horizontally according to the type of motor being tested.

What is claimed is- 1. A spark plug tester including a pair of jaw carrying members, means to pivotally connect and tension said members for causing the jaws to normally approach each other, flexible fingers attached to the inner faces of the jaws and extending outwardly therefrom at substantially right angles to the plane of said members, and hollow rivets extending through the jaws and said fingers and arranged to engage opposite points on the spark plug nut.

2. A spark plug tester including a pair of jaw carrying members, means to pivotally connect and tension said members for normally causing the jaws thereof to grip the interposed nut of a spark plug, and flexible fingers attached to the inner faces of the jaws and extending outwardly therefrom at substantially right angles to the plane of said members forgripping the body of the spark p 3. In a spark plug tester, a pair of tensioned jaws, flexible fingers extending outwardly from the jaws, and hollow rivets for securing the fingers to the jaws, the rivets being located to engage opposite sides of the spark plug nut and the fingers being adapted to grip the body of the nut-engaged plug.

4. In a spark plug tester, a pair of pivoted tensioned jaws formed to grip the spark plug nut, and flexible fingers secured to the jaws and extending outwardly therefrom, said fingers being adapted for dis aosal in gripping relation to the spark plug body.

5. In a spark plug tester, a pair of pivoted tensioned jaws formed to grip the spark plug nut, and flexible fingers secured to the jaws and extending therefrom at an angle thereto and adapted to grip the spark plug body both for supporting the jaws in place and for short circuiting the spark plug.

In testimony whereof, I affix my signature.

JOHN H. FISCHER. 

